Optical transmission device and communication device

Abstract

A optical transmission device that includes a light source, a spatial light modulator including a modulation part where a plurality of modulation regions that is irradiated with light emitted from the light source is set, a wave plate disposed in an optical path of modulated light that is modulated in each of the modulation regions set in the modulation part of the spatial light modulator, the wave plate converting the modulated light that is modulated in each of the modulation regions to mutually different polarization states, and a curved surface mirror having a curved reflection surface irradiated with the modulated light that is converted to the mutually different polarization states, the curved surface mirror reflecting the modulated light converted to the mutually different polarization states at a projection angle in accordance with a curvature of the reflection surface.

What is claimed is: 
     
         1 . A optical transmission device comprising:
 a light source;   a spatial light modulator including a modulation part where a plurality of modulation regions that is irradiated with light emitted from the light source is set, the spatial light modulator modulating a phase of the radiated light in each of the plurality of modulation regions that is set in the modulation part;   a wave plate disposed in an optical path of modulated light that is modulated in each of the plurality of modulation regions set in the modulation part of the spatial light modulator, the wave plate converting the modulated light that is modulated in each of the plurality of modulation regions to mutually different polarization states; and   a curved surface mirror having a curved reflection surface irradiated with the modulated light that is converted to the mutually different polarization states, the curved surface mirror reflecting the modulated light converted to the mutually different polarization states at a projection angle in accordance with a curvature of the reflection surface.   
     
     
         2 . The optical transmission device according to  claim 1 , further comprising:
 a partition wall that is disposed in at least any one of boundaries of the plurality of modulation regions and prevents the modulated light modulated in each of the plurality of modulation regions from being mixed.   
     
     
         3 . The optical transmission device according to  claim 1 , wherein
 the light source includes   a first light emitter and a second light emitter, and wherein   the modulation part of the spatial light modulator   is divided into a first modulation region irradiated with light emitted from the first light emitter and a second modulation region irradiated with light emitted from the second light emitter.   
     
     
         4 . The optical transmission device according to  claim 1 , wherein
 the light source includes   a first light emitter, a second light emitter, a third light emitter, and a fourth light emitter, and wherein   the modulation part of the spatial light modulator   is divided into a first modulation region including a sub-region irradiated with light emitted from each of the first light emitter and light emitted from the second light emitter, and a second modulation region including a sub-region irradiated with each of light emitted from the third light emitter and light emitted from the fourth light emitter.   
     
     
         5 . The optical transmission device according to  claim 3 , wherein
 the wave plate   includes a half-wave plate, and is installed on an optical path of the modulated light modulated in any one of the first modulation region and the second modulation region.   
     
     
         6 . The optical transmission device according to  claim 3 , wherein
 the wave plate includes   a first wave plate that includes a quarter-wave plate, is installed on an optical path of the modulated light modulated in the first modulation region, and converts the modulated light modulated in the first modulation region into circularly polarized light whose polarization direction is a first rotation direction; and   a second wave plate that includes a quarter-wave plate, is installed on an optical path of the modulated light modulated in the second modulation region, and converts the modulated light modulated in the second modulation region into circularly polarized light whose polarization direction is a second rotation direction, and wherein   a rotation direction of the first rotation direction is opposite to a rotation direction of the second rotation direction.   
     
     
         7 . The optical transmission device according to  claim 3 , wherein
 the spatial light modulator includes   a first spatial light modulator in which the first modulation region is set, and a second spatial light modulator in which the second modulation region is set, and wherein   the first spatial light modulator and the second spatial light modulator are disposed in such a way that polarization directions are perpendicular to each other.   
     
     
         8 . The optical transmission device according to  claim 1 , wherein
 the light source includes   a plurality of light emitters that emits light in different wavelength bands.   
     
     
         9 . A communication device comprising:
 the optical transmission device according to  claim 1 ;   a light-receiving device that receives a spatial optical signal transmitted from a communication target; and   a controller comprising   a memory storing instructions, and   a processor connected to the memory and configured to execute the instructions to   set a pattern for forming a spatial optical signal to be transmitted toward the communication target in each of a plurality of modulation regions set in a modulation part of a spatial light modulator of the optical transmission device,   control a light source of the optical transmission device in such a way that the modulation part in which the pattern is set is irradiated with light, and   acquire a signal derived from the spatial optical signal received by the light-receiving device.   
     
     
         10 . The communication device according to  claim 9 , wherein
 the light-receiving device includes   a concentrator that collects the spatial optical signal transmitted from another communication device,   a plurality of light receiving elements that receives an optical signal to be received among the spatial optical signals collected by the concentrator, and   a light receiving filter that is disposed in association with each of the plurality of light receiving elements and selectively transmits the optical signal to be received by the associated light receiving element.   
     
     
         11 . The communication device according to  claim 10 , wherein
 the light receiving filter includes   a polarizing plate that selectively transmits linearly polarized light in a polarization direction of the optical signal to be received by the associated light receiving element.   
     
     
         12 . The communication device according to  claim 10 , wherein
 the light receiving filter includes   a quarter-wave plate that converts the optical signal to be received by the associated light receiving element from circularly polarized light into linearly polarized light, and a polarizing plate that selectively transmits the linearly polarized light whose polarization direction is a specific direction in the linearly polarized light converted by the quarter-wave plate.   
     
     
         13 . The communication device according to  claim 10 , wherein
 the light receiving filter includes   a band pass filter that selectively transmits the optical signal in a wavelength band to be received by the associated light receiving element.